Electrosurgery in the presence of volatile anesthetic gases has
been associated with operating-room fires. We report a case in which an
operating-room fire occurred while an intubated patient underwent
electrosurgical tracheostomy. The fire in this case was caused by a
combination of an oxygen-rich environment, a polyvinyl chloride tube,
and heat generated by an electrosurgical unit. We also discuss factors
that increase the risk of this type of fire and the management steps
that should be undertaken in the event that such afire occurs, and we
briefly review the literature on this subject.

Introduction

Electrocautery procedures are a known cause of operating-room
fires. In the presence of a volatile anesthetic mixture, electrocautery
can result in the ignition of plastic, rubber, paper, and other
combustible or flammable materials.

Seven previous cases of endotracheal tube fire have been reported
in the literature. (1-7) In five of these cases, fire occurred during a
tracheostomy. (3-7) When tracheostomy is performed on an intubated
patient, an airway fire can occur when electrocautery is used to incise the trachea in close proximity to the endotracheal tube. In this
article, we report a new case of endotracheal tube fire during
tracheostomy.

Case report

A 35-year-old woman was scheduled for elective tracheostomy. The
woman had undergone an exploratory laparotomy 17 days earlier. She
subsequently developed sepsis and adult respiratory distress syndrome and was admitted to the intensive care unit (ICU). Her lungs were
ventilated through an in situ 7.5-mm internal-diameter polyvinyl
chloride endotracheal tube.

General anesthesia was induced with 6 mg of intravenous vecuronium
and maintained with isoflurane and a 100% [O.sub.2]-air mixture. The
patient was placed in the supine position and prepared and draped for
tracheostomy in the usual fashion. A grounding pad was placed on the
patient. A transverse skin incision was made two finger breadths (~2 cm)
above the sternal notch by electrocautery. The incision was carried down
to the level of the strap muscles, which were retracted laterally. The
thyroid isthmus was cut and transfixed. Electrocautery was then used to
coagulate a vessel overlying the trachea and to subsequently enter the
trachea. Before incising the trachea, 100% oxygen was used to ventilate the patient in order to maximize oxygen saturation. This was done in
anticipation of the short period of apnea that occurs when the surgeon
switches from an oral endotracheal tube to a tracheostomy tube.

When the trachea was entered, a small explosion occurred that
ignited the endotracheal tube. The oxygen source was immediately
disconnected, and the tube was removed. Immediate inspection of the
airway revealed that there was no ongoing fire. Once the patient's
safety was assured, the tracheostomy proceeded and was quickly
completed. A size 6 Shiley tracheostomy tube with cuff was placed and
secured, and the cuff was inflated.

The patient showed no outward signs of deterioration as a result of
the fire. Direct laryngoscopy was performed to assess any damage.
Examination of the oral cavity detected a charring of the postpharyngeal
wall. The anterior segment of the trachea surrounding the tracheostomy
was also charred, but the distal airway was not damaged. The cuff of the
endotracheal tube was perforated and had melted, and the proximal lumen
was full of black char.

The patient was taken back to the ICU. She underwent a chest x-ray,
which showed no change from her preoperative radiograph. Flexible
endoscopy on postoperative day 3 showed a mild staining of the
epiglottis, but the remainder of the larynx appeared to be normal. The
patient later developed pneumothorax and received a chest tube on the
left side. The patient was kept in the ICU as a result of a prolonged
illness unrelated to her tracheostomy. Despite her multiple medical
conditions, she remains alive with the tracheostomy tube still in place.
She still has no evidence of airway damage or tracheal stenosis.

Discussion

In much of the medical literature, the terms electrosurgery and
electrocautery are used interchangeably. However, they have different
meanings. Electrosurgery describes the act of coagulating or cutting by
passing a high-frequency current through tissue. Electrocautery
describes the transfer of heat from a preheated object (e.g., Shaw
scalpel) to tissue.

There are two types of electrosurgical units--unipolar and bipolar:

* Unipolar units are made up of three basic parts: a generator, an
active electrode, and a grounding pad. The generator produces a
high-density current that passes through the active electrode to the tip
of the instrument. The grounding pad collects the current and completes
the circuit.

When a unipolar unit is used in the cutting mode, the
high-frequency current passes through the target tissue, and the active
electrode functions as a bloodless knife by disintegrating the cells at
the edges of the wound. A mild thermal injury occurs away from the plane
of the cutting, and blood vessels thrombose. When the unit is set to
coagulation mode, hemostasis is achieved without cutting. The cells
undergo rapid dehydration, and the vessels coagulate. However, in some
cases, damage to adjacent tissue can be extensive. (8)

* Bipolar units are made up of a generator and two electrodes,
which are located at either end of a forceps. Current flows from one tip
of the forceps and is collected by the other to complete the circuit.
The flow of current is limited to the ends of the forceps, which
minimizes the damage to surrounding tissue.

Electrosurgery can lead to a localized fire when a small amount of
flammable material is heated to its ignition temperature. Electrosurgery
can also cause combustion by producing a spark. A spark passing through
a volume of air equal to 1 mm can reach a temperature of 1,0000[degrees]
C in 1 msec, which is certainly sufficient to ignite flammable material.
(5)

Only seven previous cases of electrocautery-induced endotracheal
tube ignition have been reported in the literature (table). Two of these
fires occurred during electrosurgical tonsillectomy. (1,2) The other
five cases occurred during tracheostomy. (3-7) In four of the latter
five cases, flashes of fire were visible outside the tracheostomy site,
indicating that the flames were vented. No smoke was seen in any of
these five cases. Finally, none of the five tracheostomy patients
sustained any distal airway bums, and in all cases, tracheal burns were
at worst superficial, localized, and inconsequential.

When an airway fire occurs during tracheostomy with an endotracheal
tube in situ just proximal to the tracheostomy opening, a
"blowtorch" flame is often seen venting out through the
tracheostomy opening. This venting can prevent extensive burn injury to
the distal aspect of the tracheobronchial tree. (1) However, if a fire
is not extinguished completely or if the heat does not dissipate
quickly, a thermal injury will probably occur.

An endotracheal tube fire is potentially fatal. In order for
combustion to take place, an ignition source (electrosurgical unit), a
carbon source (endotracheal tube), and oxygen must all be present in
close proximity. (5) A common feature of all previously reported cases
is a high oxygen concentration in the immediate environment surrounding
the tube. In such an oxygen-rich environment, a spark or high
temperature induced by electrosurgery can cause an endotracheal tube to
ignite. In our patient, the incision of the trachea by electrocautery
perforated the endotracheal tube cuff, which resulted in a back-flow of
oxygen around the tube and caused the fire.

Certain precautions can be taken to reduce the risk of endotracheal
tube fire during electrosurgery. Whenever tracheostomy is performed on
an intubated patient, electrosurgery should not be used as the
dissection proceeds close to the trachea, and it should never be used to
open the trachea. It is also desirable to ventilate the patient with the
lowest practical oxygen concentration. (9)

Every surgeon should be well aware of the procedure to follow in
the event of such an emergency. When an endotracheal tube fire is
recognized, the surgeon should immediately turn off the electrosurgical
unit and remove the electrode from the site of the fire. The
anesthesiologist should disconnect the oxygen supply and remove the
endotracheal tube from the airway, anticipating that reintubation, if
necessary, might be difficult. Examination of the oral cavity, direct
laryngoscopy, flexible endoscopy, and rigid bronchoscopy should be
performed to evaluate the extent of damage. An immediate chest x-ray
should be obtained to rule out pneumothorax. Close monitoring for a few
days in the ICU will help detect any late respiratory deterioration.
Antibiotics and steroids are recommended to reduce the risk of infection
and to subdue inflammation.

Acknowledgment

The authors are thankful to Shaikh Rahmatullah, a secretary in the
Otolaryngology--Head and Neck Surgery unit at the Aga Khan University,
for his cooperation and clerical assistance. He helped make all
necessary changes in the manuscript with pleasure.

From the Department of Surgery, Otolaryngology--Head and Neck
Surgery, The Aga Khan University Hospital, Karachi, Pakistan.